Sometimes you want to offer your users different authentication mechanisms like
a form login and a Facebook login while both entry points redirect the user to
the same login page.
However, in your configuration you have to explicitly say which entry point
you want to use.

However, there are use cases where you have authenticators that protect different
parts of your application. For example, you have a login form that protects
the secured area of your application front-end and API end points that are
protected with API tokens. As you can only configure one entry point per firewall,
the solution is to split the configuration into two separate firewalls: